This invention relates to a new and improved system for mixing fountain concentrate and water in the desired proportions continuously and automatically.
As is known, offset printing presses are usually provided with a fountain which is usually filled with a solution of gum arabic dissolved in water and a slight proportion of chromic or phosphoric acid. Such mixtures are known as "acid" type fountain solutions and have a pH of less than 7.0. More recently, alkaline fountain solutions have been developed primarily for use in printing on uncoated paper or "newsprint". These solutions are used to the largest extent on newspaper presses and consist of water mixed with a small amount of a chemical concentrate having a pH of greater than 7.0. These solutions are known as "alkaline" type fountain solutions and there exists a need for high capacity automatic mixing devices for such "alkaline" type fountain solutions.
With either type of solution damping rollers apply the fountain solution to the non-printing portions of the printing plate on the plate cylinder of the press to ensure that no ink from the inking rollers will be received on those dampened parts of the plate.
Numerous types of mixing devices for the "acid" type fountain solutions are found in the prior art and are described in the following U.S. Pat. Nos. 3,166,095; 3,223,294; 3,233,619; 3,358,704 and 3,893,470 all owned by the assignee of the present application.
All of these devices were originally adapted for the mixing of fountain solutions of the "acid" type and are quite suitable for that purpose.
Alkaline fountain solutions, as noted previously, are largely used in newspaper presses where the capacity must be very high since newspaper presses run at very high printing speeds and print many webs at a time.
The prior art devices while mechanically satisfactory for alkaline solutions lack sufficient capacity to operate satisfactorily with high speed presses. For example, some of the prior art devices function with only a two or three gallon supply of concentrate which would require frequent refilling meaning loss of time, manpower and production.
One of the features of the present invention is a capacity of over 400 gallons per hour which is approximately four times the capacity of some prior art devices. The invention further permits concentrate to be supplied from 30 or 55 gallon drums rather than the 3 gallon bottles used by some of the prior art devices while at the same time obtaining an accuracy of plus or minus one-quarter ounce of concentrate per gallon of solution.
The invention herein although developed primarily for "alkaline" solutions is also usable with "acid" solutions and for this reason the expression "concentrate" is used to connote either type of fountain concentrate.
With the foregoing in mind it is an object of this invention to provide a new and improved system for mixing concentrate and water to form fountain solutions for a printing press.
Another object of this invention is to provide a new and improved system for mixing concentrate and water having a water system, a concentrate system, a pneumatic system and means interconnecting said systems whereby the water system and the concentrate system are controlled by the pneumatic system to continuously and automatically prepare fountain solutions.
Another object of this invention is to provide a new and improved system for mixing concentrate and water having a water motor which drives a variable stroke concentrate pump.
A further object of this invention is to provide a new and improved system for mixing concentrate and water wherein the relationship of the strokes of the water motor and concentrate pump are constant during a given period of operation, but either stroke can be adjusted, so as to change concentration.
A still further object of this invention is to provide a new and improved system of mixing concentrate and water having a novel concentrate pump.
Another object of this invention is to provide a new and improved self-purging pump.
Another object of this invention is to provide a new and improved continuous system for mixing concentrate and water having a water system including a water motor, a concentrate system and a pneumatic system wherein the water system and concentrate system are controlled by the pneumatic system and wherein the pneumatic system is actuated by the water motor.
Additional objects and advantages of the invention will be set forth in the description which follows and in part will be obvious from the description. The objects and advantages being realized and obtained by means of the instrumentalities, parts, apparatus and system being particularly pointed out in the appended claims.
The invention consists of the novel parts, steps, constructions and improvements shown and described.
The invention comprises an automatic and continuous system for mixing predetermined proportions of concentrate and water.
In accordance with this invention means is provided for feeding a constant fixed amount of water into the system with means for varying, as desired, the amount of concentrate fed into the system so that a predetermined proportions of concentrate and water will be mixed.
This means includes a positive displacement pneumatically controlled water motor having a piston therein with a predetermined fixed stroke which displaces a predetermined quantity or volume of water with each stroke. This piston is connected to a lever which is pivoted intermediate of its ends. One end of the pivoted lever is connected to the piston of the positive displacement water motor and the other end is connected to a novel concentrate pump. The position of the intermediate pivot point is adjustable between the water pump and the concentrate pump and since the displacement of water motor piston is constant, the stroke of the concentrate pump can be changed and hence the proportion of concentrate to water can be varied.
The system is pneumatically controlled for reliability, convenience, low cost and safety.
The unit described herein is self-contained and needs only an outside supply of air and water for operation.
The pneumatic system is put into operation by the movement of the piston rod of the water motor which at the upper and lower ends of its stroke engages mechanically actuated pneumatic valves which control and direct the flow of air. The two valves are pneumatically connected to an air logic valve and by the momentary feeding of air can move the air logic valve from one position to another. The invention further includes two pneumatically actuated water motor valves which control the flow of water to and from the water motor. Movement of the water valve is determined by the position of the air logic valve. The air logic valve also controls movement of the concentrate control valve spool by means of a rotary air cylinder and linkage. The concentrate control valve spool is connected to a lever which lever positions the concentrate valve.
The position of the concentrate valve directs the flow of concentrate from the concentrate reservoir through the concentrate pump for ultimate mixture with the water to form the fountain solution.
The invention further includes a novel concentrate pump which is self-purging to provide increased accuracy in operation.
Briefly described, the invention comprises a system for mixing predetermined quantities of concentrate and water to form a fountain solution for use in printing presses. The invention includes a water motor and a concentrate pump. The water motor and the concentrate pump are interconnected and constructed and arranged so that the quantity of water fed into the system remains constant while the amount of concentrate fed into the system can be varied by adjusting the interconnection between the water motor and the concentrate pump.
There are first and second water motor valves which control the flow of water into and out of the water motor. The positions of the first and second water motor valves is determined by pneumatic means. There is a concentrate pump having a concentrate control valve which controls the flow of concentrate into and out of the concentrate pump. The position of the concentrate valve is determined by pneumatic means.
The water motor and the concentrate pump are interconnected by conduit means which bring the water and concentrate together for mixing purposes.
The overall and sequential operation of the system is controlled by a pneumatic control system which includes an air logic valve. The air logic valve positions the first and second water motor valves and controls the position of the concentrate valve.
There is an air supply means for the pneumatic system and a pair of mechanically actuated pneumatic valves which direct the flow of air. These valves are actuated by cams on the piston rod of the water motor which are positioned to contact one valve at each end of its stroke. The actuation of these valves determine the sequence of operation.
The accompanying drawings which are incorporated in and constitute part of this specification illustrate an embodiment of the invention and together with the description serve to explain the principles of the invention.